1. Field of the Invention
The present invention relates to a buffer, and, more particularly, to a buffer to be used in a disk drive, which may effectively protect a disk drive from impact by its excellent buffering ability, and also be manufactured in a minimal size, and a disk drive assembly including the same.
2. Description of the Related Art
A disk drive is a type of auxiliary memory device. Typical disk drives may include a hard disk drive or an optical disk drive used to read and record data stored in a magnetic or optical disk by a magnetic or optical head. For stable input of data, it is important that vibration occurring inside or outside of a disk drive is prevented or controlled, and research regarding the prevention and/or control of this vibration is actively being pursued.
A disk drive generally includes a motor to rotate a disk, and an actuator having a head used to record data to the disk and read the data recorded on the disk. An internal vibration may occur due to the motor and/or the actuator included in the disk drive. A vibration blocking mount may be used to solve this problem, thereby minimizing the rotation vibration factor caused by inner spindle force, as disclosed in U.S. Pat. No. 5,400,196. However, vibration introduced from an external source may still not be prevented.
As described above, a matter of greater concern than internal vibration is a vibration caused by an external impact. As disk drives become smaller and lighter so that they may be attached to portable devices, vibration caused by an external impact becomes a more serious matter. The external impact may cause damage to a disk drive, such as the dislocation of the rotation center of a disk, damage to the disk, interference to the normal operation of the motor, interference in reading recorded information, and magnetic or physical destruction of the recorded information.
Currently, an ultra slim disk drive is considered to be the optimal storage medium since it is cheaper than a general flash memory device with comparable capacity, and the power consumption is less than 1 W, which makes it possible to be installed in a portable device. Currently, an ultra slim disk drive is generally utilized by a portable device, and, more particularly, to a multi-media player such as an MP3 player and PMP. An ultra slim disk drive has been developed which has a thickness that has been reduced to less than 1 inch. A product whose thickness is approximately 1 inch could be, for example, an MP3 player or PMP, and a product whose thickness is less than approximately 1 inch may be applicable to, for example, a wireless AP, PDA, or navigational system.
As described above, the application range of an ultra slim disk drive is becoming extensive, but research regarding a method of protecting the disk drive from vibration due to an external impact has been thus far largely unsatisfactory. In a case in which a disk drive is installed in a portable device, since an external impact acceleration is generally not less than 5000 G, a method of protecting the disk drive from an external impact is essential. In the case in which a disk drive is installed in a portable device, vibration and impacts occur more frequently and with greater intensity than when installed in a personal computer. With a portable device, there is the problem of not installing an effective amount of buffer material, or the vibration blocking mount may not be properly installed due to the limitation of the size and weight of the disk drive.
In FIG. 1, a method of installing a vibration absorbing element different from a vibration blocking mount is illustrated. FIG. 1 illustrates a cross-sectional view of a vibration absorbing element disclosed in U.S. Pat. No. 5,349,486 (hereinafter referred to as the '486 patent). As illustrated, a magnetic disk 11 having a magnetic head 12 and a head arm 13 is surrounded by an enclosure 14 and vibration absorbing elements 15a, 15b, and 15c are interposed between the enclosure 14 and a frame 16 installed at the outer wall of the enclosure 14. In the '486 patent, it is disclosed that a spindle center 17, a shaft center 19 of an actuator, a center of gravity 20 of the enclosure 14, and rigidity factors Kc and Ks for each direction of each of vibration absorbing elements 15a, 15b, and 15c are designed via a dynamical design by using distances L1 through L5. In FIG. 1, an identifier rpos that is not described is the distance from the rotation center of the actuator to the tip of the magnetic head 12.
The absorbing element described above may be possible to design, but also may be difficult to manufacture, and the manufacturing cost may increase in the case in which the absorbing element is manufactured in a small size to control the vibration of a disk drive. Also, since the installation space is not large in the case of an ultra slim disk drive, the use of the '486 patent design may be undesirable. In the case in which a buffer having a maximum compressibility of approximately 30%, such as a rubber, is used, if the design is in the preferably small size, a space of at least 1.5 mm is required. According to Hooke's law, the rigidity is in inverse proportion to the thickness.
Also, a method of controlling an undesirable vibration of a disk drive by using a sensor, a servo algorithm, and an inertia generator in order to protect the disk drive from an impact may be considered, but it is not suitable to install an additional device for controlling vibration in an ultra slim drive. Namely, since there are limitations regarding installation space, size, and weight as characteristics of a portable device, this is not a desirable solution.